Flue damper control device for fluid fuel heated apparatus



July 27, 1955 A. DIERMAYER ETAL 3,197,139

FLUE DAMPER CONTROL DEVICE FOR FLUID FUEL HEATED APPARATUS Filed May 22, 1963 2 Sheets-Sheet 1 July 27, 1965 A. DIERMAYER ETAL 3,197,139

FLUE DAMPER CONTROL DEVICE FOR FLUID FUEL HEATED APPARATUS Filed May 22, 1963 2 Sheets-Sheet 2 United States Patent 3,197,139 FLUE DAMPER CONTRGL DEVKCE FOR FLUED FUEL HEATED APPARATUS Alphons Diermayer, 6 Baumlstrasse, and Luitpold Kntzner, 1th) Furstenriederstrasse, both of Munich, Germany Filed May 22, 1963, Ser. No. 282,285 Claims priority, application Germany,lviay 3t 1962, 1) 39,106 4 Claims. (Cl. 236--1) This invention relates to damper controls for the exhaust conduits of fuel burning heating devices, and more particularly to a temperature responsive damper control device for gas fueled burners.

When a burner is operated intermittently, and the gases of combustion are released to the atmosphere by the natural draft of a chimney and the like, cold air is drawn in through the chimney when the burner stops operation, and when the temperature in the burner room is lower than the temperature of the atmosphere. This is usually undesirable.

The object of this invention is the provision of a damper and of a damper control mechanism for controlling the flow of gas in a flue or like conduit connected to a burner and communicating with the atmosphere which automatically obstructs and substantially closes the conduit when burner operation is interrupted.

Another object is the provision of a damper mechanism which is actuated responsive to the initiation of burner operation, and itself cooperates in initiating burner operation.

A further object is the provision of a damper mechanism which operates responsive to the temperature of an exhaust gas passing through the conduit controlled by the damper mechanism, yet is insensitive to heat retained by an object heated by the hot combustion gases after burner operation has been stopped.

With these and other objects in View, the invention in one of its more specific aspects resides in a heating arrangement in which a source of gaseous fuel is connected to a burner by a valve which admits the fuel to the burner for combustion to hot exhaust gas. A conduit is provided for discharging the gas from the burner, and a damper is arranged in the conduit for movement between a conduit opening position and a conduit closing position. Movement of the damper between these positions is caused by a damper actuator which is at least partly arranged in the conduit for thermal contact with the exhaust gas, and which actuates the damper responsive to the actuator temperature.

An auxiliary mechanism is provided for heating the actuator, and has its own controls which respond to the temperature of an object heated by the exhaust gas. The fuel valve is opened and closed by a control mechanism which responds to the temperature of the actuator.

Other features of this invention and many of the attendant advantages thereof will be readily appreciated as the invention becomes better understood by reference to the following detailed description of preferred embodiments thereof, when considered in connection with the accompanying drawings in which:

FIG. 1 shows a domestic gas-fired water heater equipped with the damper and control device of the invention, the water heater being shown in elevation, and partly in section;

FIG. 2 shows a detail of the heater of FIG. 1 on an enlarged scale;

FIG. 3 is the wiring diagram of a damper control device of the invention for the water heater of FIG. 1;

FIG. 4 is the wiring diagram of a modified control device; and

3,197,139 Patented July 27, 1965 FIG. 5 is the wiring diagram of device.

Referring now to the drawing, and initially to FIG. 1, there is seen the upright'cylindrical tank 1 of 'a basically conventional gas fired domestic water heater. The'tank is mounted on a cylindrical hollow base 2 which is the outer shell of a gas burner as is usual. Fuel is supplied to the burner through a pipe 3, and the fuel supply is controlled by a solenoid valve 4 in the pipe 3. The burner will further be understood to be equipped with a fuel igniter and conventional safety devices.

The electrical controls of the water heater are supplied with alternating current through a cable 5 which is attached to a transformer housing 6 on the tank 1. The temperature of the water in the tank 1 is automatically maintained by an adjustable thermostat 7. Hot combustion gases are discharged from the burner through an exhaust fine 8 axially passing through the tank 1. A damper 9 is mounted in the line 8 on a bi-metal actuating bracket 14 in such a manner that the flue 8 is obstructed and practically closed by the damper when the bracket 10 is cold, and is fully opened when the bracket 10 is heated.

The cold and hot water connections to the tank 1 have not been illustrated since they may be entirely conventional, and are not in themselves relevant to this invention. The conductors which connect the cable 5 to the several electrically operated control elements also have not been shown for the sake of clarity, and their arrangement will be evident from the wiring diagrams of FIGS. 3, 4, and 5, each of which is applicable to the water heater of FIG. 1.

As shown in more detail in FIG. 2, the bi-metal bracket 10 is attached to the wall of the flue 8 by means of a switch housing'll. A pad 12 of insulating material is interposed between the bracket 10 and the damper 9. The bracket 10 also carries a second switch housing 13. The closed position of the damper and of associated elements is indicated in solid lines, the open position in broken outline.

A schematic wiring diagram of a first embodiment of the control device of the invention is found in FIG. 3. The two conductors 15, 15' of the cable 5 are connected to a source of alternating current. The conductor 15 is attached to one terminal of the temperature responsive switch 17 of the thermostat 7 which is the master control switch of the device. The other terminal of the switch 17 is connected to two switches 21 and 23. The switch 21 is arranged in the box 11. It is open at low temperature, and closes when the temperature rises. The'switch 23 is arranged in the box 13. It is closed atlow temperature, and opens when the temperature increases.

The switch 21 is connected to the common return'con ductor 15' through the coil 14 of the solenoid gas valve 4. The switch 23 is connected to the return conductor through the primary winding of a transformer 16 arrangedin the housing 6. The secondary winding of the transformer 16 is connected to the bi-meal bracket 10. As is shown in FIG. 3 in a somewhat schematic perspective representation, the bracket 10, and the free ends of its two branches are located on or in the switch box 11.

The afore-described apparatus operates as follows:

When the water temperature within the tank 1 is lower than the temperature for which the thermostat 7 is set, the master control switch 17 closes, as seen in FIG. 3. Current is thereby caused to flow through the normally closed heater switch 23 and the primary winding of the yet another control transformer 16. .The secondary current of the transance is also transmitted to the switch housings 11 and 13, and to the switches 21, 23 arranged therein. The valve control switch 21 is closed and energizes the solenoid coil 14 of the valve 4; Fuel .is admitted to the burner. The auxiliary heater switch 23 opens and disconnects the transformer 16 from the current source. Electrical heating of the bracket is stopped. The combustion gases of the burning fuel rising in the flue 8, however, maintain the high temperature of the bracket 10. The damper 9 remains open and the circuit of the solenoid valve 4 remains energized as long as heat is supplied by combustion of fuel in the burner.

When the water in the tank 1 reaches the temperature set on the thrmostat 7, the switch 17 is opened. The coil 14 is deenergized'and the burner flame is extinguished. The bracket 10 cools down to the temperature of the water in the tank 1. This temperature is very much lower than that of the combustion gases or that reached by the bracket 10'when current is passed therethrough from the transformer 16. The damper isclosed. While the use of temperature responsive switches in the energizing circuit of the solenoid valve 4 and in the heating circuit of the bracket 10 is preferred, other switches directly or indirectly responsive to the movement of the bracket or of the damper between the operative and inoperative position may be employed, as exemplified in the wiring diagram of FIG. 4.

The switches 21 and 23. of FIG. 3 are replaced in the arrangement of FIG. 4 by two mercury switches 18, 19 both of which will be understood to be mounted in the switch housing 13. The switches are shown in their positions. corresponding to the closed position of the damper 9. The switch 19is closed for energizing the heating transformer 16, while the switch 18 is open. When the heated bracket 10 is shifted into its operative position shown in broken outline in FIG. 2, switch 18 is closed for energizing the gas valve 4, and switch 19 is opened. The device of FIG. 4 thus opens and closes the damper 9 in the same manner as that of FIG. 3.

. If so desired, the switches 23 and 19 may be omitted so that the bi-metal bracket 10 is heated at all times when the water temperature in the tank 1 is lower than the'set temperature. This modification of the control device of the invention is applicable to the circuits of FIG. 3 as well. as FIG. 4, and the modification of the circuit of FIG. 3 has been illustrated in FIG. 5. The control device is simplified by the omission of one temperature or position responsive switch, and the operation of the damper is not affected by such omission.

. Many other modifications of the control device of the invention will readily suggest themselves. If so desired, the bracket 10 maybe heated indirectly by thermal contact with a heating element while the bracket itself is not in an electric heating circuit. Thermal energy for preheating the bracket may be derived otherwise than from a source of electric current, and the necessary modifications of the apparatus of this invention will be obvious to those skilled in the art.

The mercury switches 18,19 may be replaced by other switches responsive to the position of the bracket 10 or the damper 9.

While the invention has been described with specific reference to a damper having a single blade and a specific form of bimetallic bracket, the invention is not limited to any specific type of damper nor to the disclosed thermally responsive actuator of damper movement.

Other modifications and variationsmay obviously be resorted to by those skilled in the art without departing from the spirit and scope of the invention as hereinafter defined by the appended claims, as only preferredembodiments thereof have been disclosed.

What we claim is:

1. In a heating arrangement, in combination:

(a) a source of gaseous fuel;

(b) burner means for burning said fuel, whereby a hot exhaust gas is generated;

(c) an electrically operated valve connecting said source and said burner means;

((1) a conduit for discharging said exhaust gas from said burner means;

(e) damper means movable in said conduit between a conduit opening position and a conduit closing position;

(f) actuating means for actuating movement of said damper means between said positions thereof, a portion of said actuating means being arranged in said conduit for thermal contact with said exhaust gas and responsive to the temperature of said gas for actuating said damper means; a

(g) auxiliary heating means for raising the temperature of said actuating means;

(h) heater control means for selectively energizing said auxiliary heating means; and

(i) valve control means including a switch in circuit with said valve, said switch being in thermal contact with said actuating means and responsive to the temperature of said actuating means for opening and closing said valve.

2. In an arrangement as set forth in claim 1, auxiliary heater control means responsive to a predetermined temperature of a gas in said conduit for deenergizing said auxiliary heating means.

3. In an arrangement as set forth in claim 1, an object in thermal contact with said exhaust gas for heating thereby, said heater control means being responsive to a predetermined temperature of said object for energizing said auxiliary heating means, and for thereby causing the opening of said valve means.

' 4. In a heating arrangement, in combination:

(a) a source of fluid fuel;

(b) burner means for burning said fuel, whereby a hot exhaust gas is generated;

(c) valve means connecting said source or means;

(d) a conduit for discharging said exhaust gas from said burner means;

(e) damper means movable in said conduit between a conduit opening position and a conduit closing position;

(f) actuating means for actuating movement of said damper means between said positions thereof, a portion of said actuating means being arranged in said conduit for thermal contact with said exhaust gas, and responsive to the temperature of said gas for actuating said damper means;

(g) auxiliary heating means. for raising the temperature of said actuating means;

(h) heater control means for selectively energizing said auxiliary heating means;

(i) valve control means responsive to the temperature of said actuating means for opening and closing said valve means; and

(j) auxiliary heater control means responsive to a predetermined temperature of said actuating means for deenergizing said auxiliary heating means.

and said burn- References Cited by the Examiner UNITED STATES PATENTS Klockau 236-1 Sturgis 236-45 X Bock 2361 Olsen 236-68 X Kay 23610 X 

1. IN A HEATING ARRANGEMENT, IN COMBINATION: (A) A SOURCE OF GASEOUS FUEL; (B) BURNER MEANS FOR BURNING SAID FUEL, WHEREBY A HOT EXHAUST GAS IS GENERATED; (C)~ AN ELECTRICALLY OPERATED VALVE CONNECTING SAID SOURCE AND SAID BURNER MEANS; (D) A CONDUIT FOR DISCHARGING SAID EXHAUST GAS FROM SAID BURNER MEANS; (E) DAMPER MEANS MOVABLE IN SAID CONDUIT BETWEEN A CONDUIT OPENING POSITION AND A CONDUIT CLOSING POSITION; (F) ACTUATING MEANS FOR ACTUATING MOVEMENT OF SAID DAMPER MEANS BETWEEN SAID POSITIONS THEREOF, A PORTION OF SAID ACTUATING MEANS BEING ARRANGED IN SAID CONDUIT FOR THERMAL CONTACT WITH SAID EXHAUST GAS AND RESPONSIVE TO THE TEMPERATURE OF SAID GAS FOR ACTUATING SAID DAMPER MEANS; (G) AUXILIARY HEATING MEANS FOR RAISING THE TEMPERATURE OF SAID ACTUATING MEANS; (H) HEATER CONTROL MEANS FOR SELECTIVELY ENERGIZING SAID AUXILIARY HEATING MEANS; AND (I) VALVE CONTROL MEANS INCLUDING A SWITCH IN CIRCUIT WITH SAID VALVE; SAID SWITCH BEING IN THERMAL CONTACT WITH SAID ACTUATING MEANS AND RESPONSIVE TO THE TEMPERATURE OF SAID ACTUATING MEANS FOR OPENING AND CLOSING SAID VALVE. 